DE69901833T2 - METHOD FOR PRODUCING UV-RAY PROTECTIVE COATINGS BY PLASMA-REINFORCED Vapor Deposition - Google Patents

Abstract

This invention relates to a process for the preparation of UV protective coatings by plasma-enhanced vacuum deposition, using hydroxyphenyl-s-triazines as UV absorbers. This invention also relates to the use of hydroxyphenyl-s-triazines in plasma-enhanced vacuum depositions and to the substrates coated by this process.

Description

The invention relates to a method for producing UV protective layers by plasma-assisted vacuum deposition, using hydroxyphenyl-s-triazines as UV absorbers. A further subject of the invention is the use of hydroxyphenyl-s-triazines in plasma-assisted vacuum deposition and the substrates coated by this method.

The generation of low-temperature plasmas and the plasma-assisted deposition of thin organic or inorganic layers have been known for a long time and have been described, for example, by A. T. Bell, "Fundamentals of Plasma Chemistry" in Technology and Application of Plasma Chemistry", edited by J. R. Holahan and A. T. Bell, Wiley, New York (1974) or by H. Suhr, Plasma Chem. Plasma Process 3(1),1, (1983).

Such layers can often be used to change substrate properties in a very targeted manner. In particular, surface changes can be achieved using these processes without significantly changing or even worsening the other material properties.

EP-A-0 734 400, for example, describes the deposition of phosphorus-containing compounds to achieve flame-retardant properties of fibers and fabrics.

US 5,156,882 describes the plasma-assisted deposition of UV-absorbing layers made of TiO2 or other transition metal oxides. One problem with the deposition of inorganic oxides is that, as a rule, only insufficient adhesion to polymer substrates is achieved and, as a result, additional intermediate layers made of, for example, SiO2 must be built up. The UV-absorbing inorganic layers are generally not completely transparent in the visible range, which is disadvantageous for many applications.

Attempts have therefore been made to produce UV-absorbing coatings by depositing purely organic compounds using a plasma process.

DE 195 22 865, for example, describes a PECVD process for producing UV absorbing layers ("plasma enhanced chemical vapor deposition") with compounds which contain a structural element of the formula (A)

contain.

JP 6-25448, published on February 1, 1994, describes a process for the plasma polymerization of known UV absorbers, such as phenyl salicylates, 2-hydroxybenzophenones, hydroxyphenylbenzotriazoles and cyanoacrylates on plastic materials.

Plasma-assisted deposition of organic compounds often leads to unpredictable changes in molecular structures. This is often the case when functional groups such as OH groups are present in the molecule. These can either be oxidized or split off. The deposited film can therefore have completely different absorption properties than the originally used compound. In addition to absorption, the photochemical resistance of the deposited compound in the film can also differ from that of the original compound, so that the long-term protective effect of the deposited film can differ considerably from that which would be expected with the original compound in a conventional coating.

It has now surprisingly been found that the UV absorber class of hydroxyphenyltriazines is particularly suitable for the production of UV absorbing layers by plasma-assisted deposition.

The absorption spectra of the deposited compounds show only a slight change compared to the spectra in solution, which indicates a good retention of the molecular structure. They can be evaporated over a wide temperature range without decomposition and form clear transparent layers under the conditions of plasma deposition. In combination with a mono- or poly-olefinic unsaturated monomers, which are evaporated, can be used to produce well-adhering layers on polymer substrates.

Due to their good evaporability - without decomposition even at higher temperatures - higher molecular coloring substances such as pigments or dyes can also be evaporated and colored layers with high UV absorption can be produced.

It is also possible to first deposit the UV absorbers and then deposit a plasma-assisted scratch-resistant SiO2 layer on top.

One subject of the invention is a method for producing a coherent UV-absorbing layer on organic or inorganic substrates by means of plasma-assisted vacuum deposition, characterized in that a UV absorber of the hydroxyphenyl-s-triazine class is evaporated in a vacuum, exposed to a plasma and allowed to deposit on the substrate.

Preferred substrates are metals, semiconductors, glass, quartz or thermoplastic, cross-linked or structurally cross-linked plastics.

Silicon is particularly suitable as a semiconductor substrate, which can be in the form of “wafers”, for example.

Metals that are particularly suitable are aluminum, chromium, steel and vanadium, which are used to manufacture high-quality mirrors such as telescope mirrors or car headlight mirrors. Aluminum is particularly preferred.

Examples of thermoplastic, cross-linked or structurally cross-linked plastics are listed below.

1. Polymers of mono- and diolefins, for example polypropylene, polyisobutylene, polybutene-1, poly-4-methylpentene-1, polyisoprene or polybutadiene and polymers of cycloolefins such as cyclopentene or norbornene; also polyethylene (which may be cross-linked), for example high-density polyethylene (HDPE), high-density polyethylene and high molecular weight (HDPE-HMW), high-density polyethylene and ultra-high molecular weight (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE).

Polyolefins, i.e. polymers of monoolefins as exemplified in the previous paragraph, in particular polyethylene and polypropylene, can be produced by various processes, in particular by the following methods:

a) radical (usually at high pressure and high temperature).

b) by means of a catalyst, the catalyst usually containing one or more metals from group IVb, Vb, VIb or VIII. These metals usually have one or more ligands such as oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls, which can be either K- or o-coordinated. These metal complexes can be free or fixed to a support, such as, for example, activated magnesium chloride, titanium(III) chloride, aluminum oxide or silicon oxide. These catalysts can be soluble or insoluble in the polymerization medium. The catalysts can be active in the polymerization as such, or further activators can be used, such as, for example, metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, where the metals are elements from groups Ia, IIa and/or IIIa. The activators can be modified, for example, with additional ester, ether, amine or silyl ether groups. These catalyst systems are usually referred to as Phillips, Standard Oil Indiana, Ziegler(-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).

2. Mixtures of the polymers mentioned under 1), e.g. mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (e.g. PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (e.g. LDPE/HDPE).

3. Copolymers of mono- and diolefins with each other or with other vinyl monomers, such as ethylene-propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene-butene-1 copolymers, propylene-isobutylene copolymers, ethylene-butene-1 copolymers, ethylene-hexene copolymers, ethylene-methylpentene copolymers, ethylene-heptene copolymers, ethylene-Oc ten copolymers, propylene-butadiene copolymers, isobutylene-isoprene copolymers, ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, ethylene-vinyl acetate copolymers and their copolymers with carbon monoxide, or ethylene-acrylic acid copolymers and their salts (ionomers), and terpolymers of ethylene with propylene and a diene, such as hexadiene, dicyclopentadiene or ethylidene norbornene; furthermore mixtures of such copolymers with one another and with the polymers mentioned under 1), e.g. B. Polypropylene/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetate copolymers, LDPE/ethylene-acrylic acid copolymers, LLDPE/ethylene-vinyl acetate copolymers, LLDPE/ethylene-acrylic acid copolymers and alternating or random polyalkylene/carbon monoxide copolymers and their mixtures with other polymers such as polyamides.

4. Hydrocarbon resins (e.g. C₅-C₉) including hydrogenated modifications thereof (e.g. tackifier resins) and mixtures of polyalkylenes and starch.

5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene).

6. Copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives, such as styrene-butadiene, styrene-acrylonitrile, styrene-alkyl methacrylate, styrene-butadiene-alkyl acrylate and methacrylate, styrene-maleic anhydride, styrene-acrylonitrile-methyl acrylate; mixtures of high impact strength of styrene copolymers and another polymer, such as a polyacrylate, a diene polymer or an ethylene-propylene-diene terpolymer; and block copolymers of styrene, such as styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butylene-styrene or styrene-ethylene/propylene-styrene.

7. Graft copolymers of styrene or α-methylstyrene, such as styrene on polybutadiene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers, styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; Styrene and maleimide on polybutadiene, styrene and alkyl acrylates or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene-propylene-diene terpolymers, styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate-butadiene copolymers, as well as their mixtures with the copolymers mentioned under 6), such as those known as so-called ABS, MBS, ASA or AES polymers.

8. Halogen-containing polymers, such as polychloroprene, chlorinated rubber, chlorinated and brominated copolymers of isobutylene-isoprene (halobutyl rubber), chlorinated or chlorosulfonated polyethylene, copolymers of ethylene and chlorinated ethylene, epichlorohydrin homo- and copolymers, in particular polymers of halogen-containing vinyl compounds, such as polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride; and their copolymers, such as vinyl chloride-vinylidene chloride, vinyl chloride-vinyl acetate or vinylidene chloride-vinyl acetate.

9. Polymers derived from α,β-unsaturated acids and their derivatives, such as polyacrylates and polymethacrylates, polymethyl methacrylates impact-modified with butyl acrylate, polyacrylamides and polyacrylonitriles.

10. Copolymers of the monomers mentioned under 9) with each other or with other unsaturated monomers, such as acrylonitrile-butadiene copolymers, acrylonitrile-alkyl acrylate copolymers, acrylonitrile-alkoxyalkyl acrylate copolymers, acrylonitrile-vinyl halide copolymers or acrylonitrile-alkyl methacrylate-butadiene terpolymers.

11. Polymers derived from unsaturated alcohols and amines or their acyl derivatives or acetals, such as polyvinyl alcohol, polyvinyl acetate, stearate, benzoate, maleate, polyvinyl butyral, polyallyl phthalate, polyallyl melamine; as well as their copolymers with olefins mentioned in point 1.

12. Homo- and copolymers of cyclic ethers, such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or their copolymers with bisglycidyl ethers.

13. Polyacetals such as polyoxymethylene, as well as those polyoxymethylenes containing comonomers, such as ethylene oxide; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS.

14. Polyphenylene oxides and sulphides and their mixtures with styrene polymers or polyamides.

15. Polyurethanes derived from polyethers, polyesters and polybutadienes with terminal hydroxyl groups on the one hand and aliphatic or aromatic polyisocyanates on the other hand, as well as their precursors.

16. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides starting from m-xylene, diamine and adipic acid; polyamides made from hexamethylenediamine and iso- and/or terephthalic acid and optionally an elastomer as a modifier, e.g. poly-2,4,4-trimethylhexamethyleneterephthalamide or poly-mphenyleneisophthalamide. Block copolymers of the above-mentioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, such as e.g. with polyethylene glycol, polypropylene glycol or polytetramethylene glycol. Furthermore, polyamides or copolyamides modified with EPDM or ABS; as well as polyamides condensed during processing ("RIM polyamide systems").

17. Polyureas, polyimides, polyamide-imides, polyetherimides, polyesterimides, polyhydantoins and polybenzimidazoles.

18. Polyesters derived from dicarboxylic acids and dialcohols and/or from hydroxycarboxylic acids or the corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates, and block polyether esters derived from polyethers with hydroxyl end groups; also polyesters modified with polycarbonates or MBS.

19. Polycarbonates and polyester carbonates.

20. Polysulfones, polyethersulfones and polyetherketones.

21. Cross-linked polymers derived from aldehydes on the one hand and phenols, urea or melamine on the other hand, such as phenol-formaldehyde, urea-formaldehyde and melamine-formaldehyde resins.

22. Drying and non-drying alkyd resins.

23. Unsaturated polyester resins derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols, as well as vinyl compounds as crosslinking agents, as well as their halogen-containing, flame-retardant modifications.

24. Crosslinkable acrylic resins derived from substituted acrylic acid esters, such as epoxy acrylates, urethane acrylates or polyester acrylates.

25. Alkyd resins, polyester resins and acrylate resins crosslinked with melamine resins, urea resins, isocyanates, isocyanurates, polyisocyanates or epoxy resins.

26. Crosslinked epoxy resins derived from aliphatic, cycloaliphatic, heterocyclic or aromatic glycidyl compounds, e.g. products of bisphenol A diglycidyl ethers, bisphenol F diglycidyl ethers, which are crosslinked using conventional hardeners such as anhydrides or amines with or without accelerators.

27. Natural polymers such as cellulose, natural rubber, gelatin, as well as their polymer-homologously chemically modified derivatives such as cellulose acetates, propionates and butyrates, or the cellulose ethers such as methylcellulose; as well as rosin resins and derivatives.

28. Mixtures (polyblends) of the aforementioned polymers, such as PP/EPDM, polyamide/- EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/- acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC.

The thermoplastic, cross-linked or structurally cross-linked plastic is preferably a polyolefin, polyamide, polyacrylate, polycarbonate, polystyrene or an acrylic/melamine, alkyd or polyurethane varnish.

Polycarbonate is particularly preferred.

The plastics can be in the form of films, injection-molded parts, extruded workpieces, fibers, felts or fabrics.

In addition to components for the automotive industry, objects such as glasses or contact lenses can also be equipped with a thin UV-absorbing layer.

Preferably, the UV absorbers of the hydroxyphenyl-s-triazine class have a molecular weight of less than 1000.

Preferred UV absorbers of the hydroxyphenyl-s-triazine class are compounds of formula I or II

wherein

n is 1 or 2,

R₁ and R₂ independently of one another represent H, OH, C₁-C₁₂-alkyl or halomethyl,

R₅ and R₄ independently of one another represent H, OH, C₁-C₁₂-alkyl, C₁-C₁₈-alkoxy or halogen and in the case of n = 1 can also represent a radical -OR₇,

R₅ and R₆ independently of one another represent H, C₁-C₁₂-alkyl or halogen,

R₇, when n is 1, is hydrogen, C₁-C₁₈-alkyl or C₁-alkyl which is substituted by OH, d-C₁₈-alkoxy, halogen, phenoxy or phenoxy substituted by C₁-C₁₈-alkyl, C₁-C₁₈-alkoxy or halogen, -COOH, -COOR₇, -CONH₂, -CONHR₆, -CON(R₆)(R₁₀), -NH₂, -NHR₆, -N(R₆)(R₁₀), -NHCOR₁₁, -CN

and/or -OCOR₁₁, or R₇ is C₄-C₂o-alkyl, Ca-C₆-alkenyl, glycidyl, C₅-C₈-cycloalkyl, cyclohexyl, substituted by OH, C₁-C₄-alkyl or -OCOR₁₁, unsubstituted or substituted by OH, Cl or CH₃, C₇-C₁₁-phenylalkyl, -CO-R₁₂ or -SO₂-R₁₃ and when n is 2, C₂-C₁₆-alkylene, C₄-C₁₆-alkenylene, xylylene, C₃-C₂�0-alkylene interrupted by one or more O and/or substituted by OH, a group -CH₂CH(OH)CH₂O-R₁₅-OCH₂CH(OH)CH₂-, -CO-R₁₆-CO-, -CO-NH-R₁₇-NH-CO- or -(CH₂)m-COO-R₁₈-OCO-(CH₂)m-, wherein m is 1-3,

R₈ is C₁-C₁�8-alkyl, C₃-C₁�8-alkenyl, C₃-C₂�0-alkyl interrupted by O, N or S and/or substituted by OH, C₁-C₂₀-alkyl substituted by -P(O)(OR₁₄)₂, -N(R₉)(R₁₀) or -OCOR₁₁ and/or OH, glycidyl, cyclohexyl or C₇-C₁₁-phenylalkyl,

R�9 and R₁₀ independently of one another are C₁-C₁₂-alkyl, C₃-C₁₂-alkoxyalkyl, C₄-C₁₆-dialkylaminoalkyl or C₅-C₁₂-cycloalkyl or

R�9 and R₁₀ together represent C₃-C�9 alkylene or oxaalkylene or azaalkylene,

R&sub1;&sub1; C1 -C18 alkyl, C2 -C18 alkenyl or phenyl,

R&sub1;&sub2; C1 -C18 alkyl, C2 -C18 alkenyl, phenyl, C1 -C12 alkoxy, phenoxy, C1 -C12 alkylamino, phenylamino, tolylamino or naphthylamino ,

R&sub1;&sub3; C1 -C12 alkyl, phenyl, naphthyl or C7 -C14 alkylphenyl,

R₁₄ is C₁-C₁₂-alkyl or phenyl,

R₁₅ is C₂-C₁₀-alkylene, phenylene or a group -phenylene-X-phenylene-, wherein X is -O-, -S-, -SO₂-, -CH₂- or -C(CH₃)₂-,

R₁₆ is C₂-C₁₀-alkylene, -oxaalkylene or -thiaalkylene, phenylene, naphthylene, diphenylene or C₂-C₆-alkenylene,

R₁₇ represents C₂-C₁₀-alkylene, phenylene, naphthylene, methylenediphenylene or C₇-C₁₅-alkylphenylene,

R₁₋ is C₂-C₁�0 alkylene or C₄-C₂�0 alkylene interrupted by O and

R₁₉ and R₂₀ are independently H, OH, C₁-C₁₂-alkyl, C₁-C₁₂-alkoxy, NH₂, NHR₉, NR₉R₁₀ or halogen.

Halogen means chlorine, bromine or iodine. Chlorine is preferred.

Alkyl with up to 18 carbon atoms means a branched or unbranched radical such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2- ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n- heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, Tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl.

Alkenyl with 3 to 18 carbon atoms means a branched or unbranched radical such as propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2- butenyl, n-2-octenyl, n-2-dodecenyl, iso-dodecenyl, oleyl, n-2-octadecenyl or n-4-octadecenyl.

C₇-C₉-Phenylalkyl means, for example, benzyl, α-methylbenzyl, α,α-dimethylbenzyl or 2-phenylethyl. Benzyl and α,α-dimethylbenzyl are preferred.

C5 -C8 cycloalkyl that is unsubstituted or substituted with C1 -C4 alkyl means, for example, cyclopentyl, methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, tert-butylcyclohexyl, cycloheptyl or cyclooctyl.

Alkoxy with up to 18 carbon atoms means a branched or unbranched radical such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, pentoxy, isopentoxy, hexoxy, heptoxy, octoxy, decyloxy, tetradecyloxy, hexadecyloxy or octadecyloxy.

C₁-C₁₈-Alkylene means a branched or unbranched radical such as, for example, methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene or octadecamethylene.

A preferred subgroup of compounds of formula I or II are those in which n is 1 or 2,

R₁ and R₂ independently of one another represent H, OH or C₁-C₄-alkyl,

R₃ and R₄ independently of one another represent H, OH, C₁-C₄-alkyl, C₁-C₄-alkoxy, halogen or a radical -OR₇,

R�5 and R�6 independently represent H or C₁-C₄-alkyl,

R₇, when n is 1, is hydrogen, C₁-C₁₈-alkyl, C₁-C₁₈-alkyl substituted by OH, C₁-C₁₈-alkoxy, phenoxy, -COOR₇, -CONHR₉, -CON(R₇)(R₁₀) and/or -OCOR₁₁, allyl, glycidyl or benzyl, and when n is 2, is C₄-C₁₂-alkylene, C₄-C₁₈-alkenylene, xylylene or C₃-C₂₈-alkylene interrupted by one or more O and/or substituted by OH,

R₈ is C₁-C₁₂-alkyl, C₃-C₁₈-alkenyl, C₃-C₂�0-alkyl interrupted by O and/or substituted by OH or C₁-C₄-alkyl substituted by -P(O)(OR₁₄)₂,

R₉ and R₁₀ independently of one another are C₁-C₈-alkyl or cyclohexyl, or R₉ and R₁₀ together are pentamethylene or 3-oxapentamethylene,

R₁₁ is C₁-C₈-alkyl, C₂-C₅-alkenyl or phenyl and

R₁₄ is C₁-C₄-alkyl and

R₁₉ and R₂₀ independently of one another represent H, OH, C₁-C₆ alkyl, C₁-C₈ alkoxy or halogen.

Particularly preferred are compounds of formula I or II, wherein

n is 1 or 2,

R₁ and R₂ independently of one another represent H or CH₃,

R₃ and R₄ independently represent H, CH₃ or Cl,

R�5 and R�9 are hydrogen,

R₇, when n is 1, is hydrogen, C₁-C₁₂alkyl, C₁-C₄alkyl substituted by OH, C₄-C₁₈alkoxy, -COOR₈-, -CON(R₉)(R₁₀) and/or -OCOR₁₁, glycidyl or benzyl, and when n is 2, is C₆-C₁₂alkylene, 2-butenylene, 1,4-xylylene or C₃-C₂₀alkylene interrupted by O and/or substituted by OH,

R₈ is C₄-C₁₂-alkyl, C₁₂-C₁�8-alkenyl, C₆-C₂�0-alkyl interrupted by O and/or substituted by OH or C₁-C₄-alkyl substituted by -P(O)(OR₁₄)₂,

R�9 and R₁₀ are C₄-C₈-alkyl,

R₁₁ is C₁-C₈-alkyl or C₂-C₃-alkenyl and

R₁₄ is C₁-C₄-alkyl and

R₁₉ and R₂₀ independently of one another represent H, C₁-C₄-alkyl or C₁-C₄-alkoxy.

Particularly preferred are compounds of formula I or II, wherein

n is 1 or 2 and R₇, when n is 1, is a group -CH₂CH(OH)CH₂O-R₂₁, wherein R₂₁ is C₁-C₁₂alkyl, phenyl, phenyl substituted by C₁-C₁₂alkyl, C₁-C₁₂alkoxy or halogen or C₃-C₅ alkenoyl,

and when n is 2, R₇ represents a group -CH₂CH(OH)CH₂O-R₁₅-OCH₂CH(OH)CH₂-, wherein R₁₅ has the meaning given in claim 4.

Examples of individual compounds of formula I are the following compounds

R7 = -H

-C₂H�5;

-C₄H₄

-C₈H₁₇

-C₁₂H₂₅

-C₁₈H₃₇

-Cyclohexyl

-CH₂Phenyl

-CH₂CH₂OH

-CH₂CH₂OCOCH₃;

-CH2 CH2 OCOH=CH2

-CH2 CH(OH)C8 H17

-CH2 CH(OH)C12 H25

-CH2 CH(OH)CH2 OC8 H17

-CH2 CH(OH)CH2 OPhenyl

-CH2 CH(OH)CH2 OCOC(CH3 )=CH2

-CH2COOH

-CH2 CH2 COOC4 H9

-CH2 COOC8 H17

-CH2 COO(CH2 CH2 O)7 H

-CH2 COOCH2 CH(OH)CH2 OC4 H9

-CH2 COOCH2 CH(CH3 )OCH2 CH(CH3 )OCH(CH3 )CH3

-CH2 COOCH2 P(O)(OC2 H5 )2

-CH2 COOCH2 CH(OH)CH2 P(O)(OC4 H9 )2

-CH2 COO(CH2 )7 CH=CHC8 H17

-CH2 COOCH2 CH2 OCH2 CH2 OC6 H13

-CH2 CON(C2 H5 )2

Other connections are:

R�7 = -C₄H�9

-C₈H₁₇

-C₁₂H₂₅

-CH2 CH(OH)CH2 OC8 H17

-CH2COOC2H5

-CH2COOCH2OCH3

-CH2 COOCH2 CH=CH-phenyl

-CH2 COOCH2 CH(OH)CH2 OC8 H17

-CH2Phenyl

-CH2CH=CH2

-CH2 CON(C4 H9 )2

-CH2 CH2 CONH8 H17

-CO-OC₆H₁₃

-CH₂CH₂Cl

-CH₂CH₂CN and compounds

R7 = -H

-CH3;

-C₃H�7;

-C₆H₁₃

-C₈H₁₇

-C₁₂H₂₅

-CH2 CH(OH)CH2 OC8 H17

-CH₂CH(OH)Phenyl

-CH2 CH(OH)CH2 OCOPhenyl

-CH2 CH(CH3 )OCOCH3

-SO2 -C12 H15

-CH2 COOC10 H21

-CH2 CONHCH2 CH2 OCH3

-CH2 CH2 CONHCH2 phenyl

-(CH2 )3 CONH(CH2 )3 N(C2 H5 )2

-CH2 CONHC12 H25

Other suitable compounds are:

R&sub7; = -CH2 CH(OH)CH2 -

-CH₂-CH=CH-CH₂-

-(CH₂)₄-

-(CH₂)₆-

-(CH2)8

-(CH₂)₁₂-

-CH2 CH(OH)CH2 O-CH2 CH2 -OCH2 CH(OH)CH2 -

-CH2 CH(OH)CH2 O-(CH2 )6 -OCH2 CH(OH)CH2 -

-CH2 COO-(CH2 )6 -OCOCH2

-CO-(CH2)8-CO-;

R7 = -H

-C₄H₄

-C₈H₁₇

-C₁₈H₃₇

-CH2CH(OH)CH3

-CH2 CH2 OC4 H9

-CH2 CH2 COC2 H5

-CH2 COOC8 H17

-CH2 CH(OH)CH2 OC4 H9

-CH2 CH(OH)CH2 OPphenyl;

R�7 = -C₂H�5

-C₄H₄

-C₆H₁₃

-C₈H₁₇

-CH₂CH₂OH

-CH₂CH₂OPhenyl

-CH2 COOC6 H13

-CH2 CH2 COO(CH2 CH2 O)3 H

-CH2 CH(OH)CH2 OC6 H13

-CH₂CH(OH)CH₂Phenyl

A further preferred form of the method is characterized in that a dye or a colored pigment is evaporated simultaneously with the UV absorber or subsequently, exposed to a plasma and the pigment and UV absorber are deposited on the substrate.

Suitable pigments or dyes are those that can be evaporated without decomposition under plasma conditions. They are commercially available and their suitability can be checked by simply trying them out.

Also preferred is a process which is characterized in that a mono- or polyolefinically unsaturated compound is evaporated simultaneously with the UV absorber, exposed to a plasma and allowed to deposit on the substrate.

The unsaturated compounds can contain one or more olefinic double bonds. They can be low molecular weight (monomeric) or high molecular weight (oligomeric). Examples of monomers with a double bond are alkyl or hydroxyalkyl acrylates or methacrylates, such as methyl, ethyl, butyl, 2-ethylhexyl or 2-hydroxyethyl acrylate, isobornyl acrylate, methyl or ethyl methacrylate. Silicone acrylates are also interesting. Other examples are acrylonitrile, acrylamide, methacrylamide, N-substituted (meth)acrylamides, vinyl esters such as vinyl acetate, vinyl ethers such as isobutyl vinyl ether, styrene, alkyl and halostyrenes, N-vinylpyrrolidone, vinyl chloride or vinylidene chloride.

Examples of monomers with multiple double bonds are ethylene glycol, propylene glycol, neopentyl glycol, hexamethylene glycol or bisphenol A diacrylate, 4,4'-bis(2-acryloyloxyethoxy)diphenylpropane, trimethylolpropane triacrylate, pentaerythritol triacrylate or tetraacrylate, vinyl acrylate, divinylbenzene, divinyl succinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate, tris(hydroxyethyl) isocyanurate triacrylate or tris(2-acryloylethyl)isocyanurate.

Examples of higher molecular weight (oligomeric) polyunsaturated compounds are acrylated epoxy resins, acrylated polyesters, polyurethanes and polyethers containing vinyl ether or epoxy groups. Other examples of unsaturated oligomers are unsaturated polyester resins, which are usually made from maleic acid, phthalic acid and one or more diols and have molecular weights of around 500 to 3000. In addition, vinyl ether monomers and oligomers, as well as maleate-terminated oligomers with polyester, polyurethane, polyether, polyvinyl ether and epoxy main chains can also be used. In particular, combinations of oligomers and polymers carrying vinyl ether groups, as described in WO 90/01512, are particularly suitable. But copolymers of vinyl ether and maleic acid-functionalized monomers are also possible. Such unsaturated oligomers can also be called prepolymers.

Particularly suitable are, for example, esters of ethylenically unsaturated carboxylic acids and polyols or polyepoxides, and polymers with ethylenically unsaturated groups in the chain or in side groups, such as unsaturated polyesters, polyamides and polyurethanes and copolymers thereof, alkyd resins, polybutadiene and butadiene copolymers, polyisoprene and isoprene copolymers, polymers and copolymers with (meth)acrylic groups in side chains, and mixtures of one or more such polymers.

Examples of unsaturated carboxylic acids are acrylic acid, methacrylic acid, crotonic acid, itaconic acid, cinnamic acid, unsaturated fatty acids such as linolenic acid or oleic acid. Acrylic and methacrylic acid are preferred.

Aromatic and especially aliphatic and cycloaliphatic polyols are suitable as polyols. Examples of aromatic polyols are hydroquinone, 4,4'-dihydroxydiphenyl, 2,2- di(4-hydroxyphenyl)-propane, as well as novolaks and resoles. Examples of polyepoxides are those based on the polyols mentioned, especially aromatic polyols and epichlorohydrin. Furthermore, polymers and copolymers that contain hydroxyl groups in the polymer chain or in side groups, such as polyvinyl alcohol and copolymers thereof or polymethacrylic acid hydroxyalkyl esters or copolymers thereof, are also suitable as polyols. Other suitable polyols are oligoesters with hydroxyl end groups.

Examples of aliphatic and cycloaliphatic polyols are alkylenediols with preferably 2 to 12 C atoms, such as ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, pentanediol, hexanediol, octanediol, dodecanediol, diethylene glycol, triethylene glycol, polyethylene glycols with molecular weights of preferably 200 to 1500, 1,3-cyclopentanediol, 1,2-, 1,3- or 1,4-cyclohexanediol, 1,4-dihydroxymethylcyclohexane, glycerin, tris-(β-hydroxyethyl)amine, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol.

The polyols can be partially or completely esterified with one or more unsaturated carboxylic acids, whereby in partial esters the free hydroxyl groups can be modified, e.g. etherified or esterified with other carboxylic acids.

Examples of esters are:

Trimethylolpropane triacrylate, trimethylolethane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol-te traacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octa-acrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol tetramethacrylate, tripentaerythritol octamethacrylate, pentaerythritol diitaconate, dipentaerythritol trisitaconate, dipentaerythritol pentaitaconate, Dipentaerythritol hexaitaconate, ethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol di-itaconate, sorbitol triacrylate, sorbitol tetraacrylate, pentaerythritol-modified triacrylate, sorbitol tetramethacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, oligoester acrylates and methacrylates, glycerol di- and triacrylate, 1,4-cyclohexane diacrylate, bisacrylates and bismethacrylates of polyethylene glycol with molecular weight of 200 to 1500, or mixtures thereof .

The amides of identical or different unsaturated carboxylic acids of aromatic, cycloaliphatic and aliphatic polyamines with preferably 2 to 6, particularly 2 to 4 amino groups are also suitable as components. Examples of such polyamines are ethylenediamine, 1,2- or 1,3-propylenediamine, 1,2-, 1,3- or 1,4-butylenediamine, 1,5-pentylenediamine, 1,6-hexylenediamine, octylenediamine, dodecylenediamine, 1,4'-diaminocyclohexane, isophoronediamine, phenylenediamine, bisphenylenediamine, di-β-aminoethyl ether, diethylenetriamine, triethylenetetramine, di(β-aminoethoxy)- or di(β-aminopropoxy)ethane. Other suitable polyamines are polymers and copolymers with optionally additional amino groups in the side chain and oligoamides with amino end groups. Examples of such unsaturated amides are: methylene-bis-acrylamide, 1,6-hexamethylene-bis-acrylamide, diethylenetriamine-tris-methacrylamide, bis(methacrylamidopropoxy)ethane, β-methacrylamidoethyl methacrylate, N[(β-hydroxyethoxy)ethyl]-acrylamide.

Suitable unsaturated polyesters and polyamides are derived, for example, from maleic acid and diols or diamines. The maleic acid can be partially replaced by other dicarboxylic acids. They can be used together with ethylenically unsaturated comonomers, e.g. styrene. The polyesters and polyamides can also be derived from dicarboxylic acids and ethylenically unsaturated diols or diamines, especially from longer-chain ones with, for example, 6 to 20 carbon atoms. Examples of polyurethanes are those that are made up of saturated or unsaturated diisocyanates and unsaturated or saturated diols.

Polybutadiene and polyisoprene and copolymers thereof are known. Suitable comonomers are, for example, olefins such as ethylene, propene, butene, hexene, (meth)acrylates, acrylonitrile, styrene or vinyl chloride. Polymers with (meth)acrylate groups in the side chain are also known. These can, for example, be reaction products of novolak-based epoxy resins with (meth)acrylic acid, homo- or copolymers of vinyl alcohol or their hydroxyalkyl derivatives esterified with (meth)acrylic acid, or homo- and copolymers of (meth)acrylates esterified with hydroxyalkyl (meth)acrylates.

Particularly preferably, an acrylate or methacrylate compound is used as the mono- or polyunsaturated olefinic compound.

Polyunsaturated acrylate compounds, as already listed above, are particularly preferred.

The process can also be carried out in such a way that the UV absorber is evaporated together with the pigment and an olefinically unsaturated compound.

Possibilities for obtaining plasmas under vacuum conditions have been described many times in the literature. The electrical energy can be coupled in inductively or capacitively. It can be direct current or alternating current, whereby the frequency of the alternating current can vary from a few kHz up to the megahertz range. Feeding in the microwave range (giga-Hz) is also possible.

For example, He, argon, xenon, N₂, O₂ or air can be used as primary plasma gases. Non-reactive gases such as He, argon or xenon are preferred. When the UV absorber is evaporated, it mixes with the plasma gas and is also ionized.

The method according to the invention is in itself not sensitive to the gas supplied and the coupling of electrical energy. The decisive factor is that it is carried out at a relatively low pressure.

The pressure is preferably from 10⁻⁶ mbar to 10⁻² mbar, particularly preferably 10⁻³ to 10⁻⁴ mbar.

The material can, for example, be applied to a plasma electrode and vaporized directly from there. Preferably, however, the material to be vaporized is located on a separately heatable plate or a crucible that is located outside the plasma discharge. The crucible or plate can be at a positive or negative electrical potential relative to the plasma.

For example, JP 6-25448 specifies suitable embodiments for generating the plasma and for deposition.

The temperature at which the UV absorber is evaporated is preferably 20°C to 350°C, particularly preferably 100°C to 250°C.

The process is preferably carried out according to the Valico process of Rowo Coating described in WO 96/15544.

The method is particularly suitable for depositing thin layers. Preferably, the deposited layer has a thickness of 10 nm to 1000 nm, particularly preferably from 50 nm to 500 nm and very particularly preferably from 100 nm to 300 nm.

Further objects of the invention are the use of a UV absorber of the hydroxyphenyl-s-triazine class for producing UV-absorbing layers in a plasma-assisted vacuum deposition.

The following examples illustrate the invention.

To carry out the plasma-assisted deposition, a laboratory system from ROWO Coating, Herbolzheim, is used, which works according to the so-called VALICO process (anodic arc, WO 96/15544).

Approximately 20-25 g of the material to be evaporated are placed in a molybdenum crucible in an electric evaporator unit. The system is then evacuated to about 1 x 10⊃min;⊃4; mbar. After heating up the thermal evaporator, a control valve is used to set a constant system pressure of about 2-3 x 10⊃min;⊃4; mbar. The arc is then ignited and the deposition is carried out. The distance between the evaporator crucible and the substrate is 50 cm.

The layer thickness is determined by AFM (atomic force microscopy, edge measurement).

The transmission is measured with a spectral photometer Shimadsu UV-2102/3102 PC.

To estimate the adhesive strength, a simple tape test is carried out using Tesa® adhesive tape with a peel angle of approximately 60º.

example 1 Plasma-assisted deposition of a UV protective layer by evaporation of a triazine with a low extinction coefficient (Tinuvin 1577)

UV absorber Tinuvin® 1577

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 150

Arc current [A] 20

Potential difference [V] 100

Duration [s] 180

Layer aspect transparent, colorless

Layer thickness [nm] 320

Transmission (380 nm) [%] 15

Liability layer deduction

Comparison example A Purely thermal deposition of a UV protective layer by evaporation of a triazine with a low extinction coefficient (Tinuvin 1577)

UV absorber Tinuvin® 1577

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 150

Arc current [A] -

Potential difference [V] -

Duration [s] 90

Layer aspect milky cloudy

Layer thickness [nm] approx. 2000

Transmission (380 nm) [%] 2

Liability layer deduction

Example 2 Plasma-assisted deposition of a UV protective layer by evaporation of a triazine with a high extinction coefficient

UV absorber UVA-1

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 132

Arc current [A] 100

Potential difference [V] 12

Duration [s] 300

Layer aspect transparent, colorless

Layer thickness [nm] 420

Transmission (380 nm) [%] 2

Liability layer deduction

Example 3 Plasma-assisted deposition of a strong UV protective layer by co-evaporation of a triazine with a high extinction coefficient and a triacrylate

UV absorber UVA-1

Acrylate Tris(hydroxyethyl) isocyanurate triacrylate

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 132

Arc current [A] 100

Potential difference [V] 12

Duration [s] 300

Layer aspect transparent, colorless

Layer thickness [nm] 500

Transmission (380 nm) [%] 5

Liability no layer deduction

Example 4 Plasma-assisted deposition of a strong UV protective layer by evaporation of an acrylate-functionalized triazine

UV absorbers UVA-2

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 95

Arc current [A] 50

Potential difference [V] 5

Duration [s] 480

Layer aspect transparent, colorless

Layer thickness [nm] 400

Transmission (380 nm) [%] 20

Liability no layer deduction

Comparison example B Thermal deposition of a (non) adhesive UV protective layer by evaporation of an acrylate-functionalized triazine

Sunscreen CG29-0191

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 95

Arc current [A] -

Potential difference [V] -

Duration [s] 480

Layer aspect cloudy, colorless

Layer thickness [nm] 600

Transmission (380 nm) [%] 10

Adhesion complete layer removal

Example 5 Plasma-assisted deposition of a strong, colored UV protective layer by evaporating a triazine with a high extinction coefficient together with an acrylate and a pigment

UV absorber UVA-1

Acrylate Tris(hydroxyethyl) isocyanurate triacrylate,

Pigment Iragzin® DPP Red BO

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 95

Arc current [A] 50

Potential difference [V] 5

Duration [s] 420

Layer aspect transparent, red

Layer thickness [nm] 300

Transmission (380 nm) [%] 15

Liability no layer deduction

Comparison example C Thermal deposition of a (non) adhesive, colored UV protective layer by evaporation of a triazine with a high extinction coefficient together with an acrylate and a pigment

UV absorber UVA-1 Tris(hydroxyethyl) isocyanuratriacrylate, Iragzin DPP Red BÖ

Substrate polycarbonate

System pressure 3 · 10⊃min;⊃4; mbar

Evaporator power [W] 95

Arc current [A] -

Potential difference [V] -

Duration [s] 420

Layer aspect cloudy, red

Layer thickness [nm] 400

Transmission (380 nm) [%] 10

Liability complete layer removal

Claims (1)

1. Process for producing a continuous UV-absorbing layer on organic or inorganic substrates by means of plasma-assisted vacuum deposition, characterized in that a UV absorber of the hydroxyphenyl-s-triazine class is evaporated in a vacuum, exposed to a plasma and allowed to deposit on the substrate. 2. Process according to claim 1, characterized in that a metal, a semiconductor, glass, quartz or a thermoplastic, cross-linked or structurally cross-linked plastic is used as the substrate. 3. Process according to claim 2, characterized in that the thermoplastic, cross-linked or structurally cross-linked plastic is polyolefin, polyamide polyacrylate, polycarbonate, polystyrene, acrylic/melamine, alkyd or polyurethane lacquer. 4. Process according to claim 1, characterized in that a compound of formula I or II is used as UV absorber of the hydroxyphenyl-s-triazine class wherein n is 1 or 2, R₁ and R₂ independently of one another represent H, OH, C₁-C₁₂-alkyl or halomethyl, R₃ and R₄ independently of one another represent H, OH, C₁-C₁₂-alkyl, C₁-C₁₈-alkoxy or halogen and in the case of n = 1 can also represent a radical -OR₇, R₅ and R₆ independently of one another represent H, C₁-C₁₂-alkyl or halogen, R₇, when n is 1, is hydrogen, C₁-C₁₈alkyl or C₁-C₁₂alkyl substituted by OH, C₁-C₁₈alkoxy, halogen, phenoxy or phenoxy substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy or halogen, -COOH, -COOR₇, -CONH₂, -CONHR₇, -CON(R₇)(R₁₀), -NH₂, -NHR₇, -N(R₇)(R₁₀), -NHCOR₁₁, -CN and/or -OCOR₁₁, or R₇ is C₄-C₂�0 alkyl, C₃-C�6 alkenyl, glycidyl, C₅-C�8 cycloalkyl interrupted by one or more O and substituted by OH or C₁-C₁₈ alkoxy, cyclohexyl substituted by OH, C₁-C₄ alkyl or -OCOR₁₁, unsubstituted or substituted by OH, Cl or CH₃ C₇-C₁₁ phenylalkyl, -CO-R₁₂ or -SO₂-R₁₃ and when n is 2, Cz-C₁₆-alkylene, C₄-C₁₂-alkenylene, xylylene, C₃-C₂�0-alkylene interrupted by one or more O and/or substituted by OH, a group -CH₂CH(OH)CH₂O-R₁₅-OCH₂CH(OH)CH₂-, -CO-R₁₆-CO-, -CO-NH-R₁₇-NH-CO- or -(CH₂)m-COO-R₁₈-OCO-(CH₂)m-, wherein m is 1-3, R₉ and R₁₀ independently of one another are C₁-C₈-alkyl or cyclohexyl, or R₉ and R₁₀ together are pentamethylene or 3-oxapentamethylene, R₁₁ is C₁-C₈-alkyl, C₂-C₅-alkenyl or phenyl and R₁₄ is C₁-C₄-alkyl and R₁₉ and R₂₀ independently of one another are H, OH, C₁-C₈-alkyl, C₁-C₈-alkoxy or halogen. 6. Process according to claim 4, characterized in that in the compounds of the formula I or II n is 1 or 2, R₁ and R₂ independently of one another represent H or CH₃, R₃ and R₄ independently represent H, CH₃ or Cl, R�5 and R�6 are hydrogen, R₇, when n is 1, is hydrogen, C₁-C₁₂alkyl, C₁-C₄alkyl substituted by OH, C₄-C₁₈alkoxy, -COOR₇, -CON(R₇)(R₁₀) and/or -OCOR₁₁, glycidyl or benzyl, and when n is 2, is C₆-C₁₂alkylene, 2-butenylene, 1,4-xylylene or C₃-C₂₀alkylene interrupted by O and/or substituted by OH, R₈ is C₄-C₁₂-alkyl, C₁₂-C₁�8-alkenyl, C₆-C₂�0-alkyl interrupted by O and/or substituted by OH or C₁-C₄-alkyl substituted by -P(O)(OR₁₄)₂, R�9 and R₁₀ are C₄-C₈-alkyl, R₁₁ is C₁-C₈-alkyl or C₂-C₃-alkenyl and R₁₄ is C₁-C₄-alkyl and R₁₉ and R₂₀ independently of one another represent H, C₁-C₄-alkyl or C₁-C₄-alkoxy. 7. Process according to claim 4, characterized in that in the compounds of the formula I or II n is 1 or 2 and R₇, when n is 1, is a group -CH₂CH(OH)CH₂O-R₂₁, wherein R₂₁ is C₁-C₁₂alkyl, phenyl, phenyl substituted by C₁-C₁₂alkyl, C₁-C₁₂alkoxy or halogen or C₃-C₅ alkenoyl, and when n is 2, R₇ represents a group -CH₂CH(OH)CH₂O-R₁₅-OCH₂CH(OH)CH₂-, wherein R₁₅ has the meaning given in claim 4. 8. Process according to claim 1, characterized in that the pressure is from 10⁻⁶ mbar to 10⁻² mbar. 9. Process according to claim 1, characterized in that the temperature at which the UV absorber is evaporated is between 20ºC and 350ºC. 10. The method according to claim 1, characterized in that the deposited layer has a thickness of 10 nm to 1000 nm. 11. Process according to claim 1, characterized in that a dye or a color pigment is evaporated simultaneously with the UV absorber or subsequently, exposed to a plasma and deposited on the substrate. 12. Process according to claim 1, characterized in that a mono- or polyolefinically unsaturated compound is evaporated simultaneously with the UV absorber, exposed to a plasma and deposited on the substrate. 13. Process according to claim 12, characterized in that an acrylate or methacrylate compound is used as the mono- or polyunsaturated olefinic compound. 14. Use of a UV absorber of the hydroxyphenyl-s-triazine class for producing UV absorbing layers in a plasma-assisted vacuum deposition.